// ==========================================================
// FreeImage 3 .NET wrapper
// Original FreeImage 3 functions and .NET compatible derived functions
//
// Design and implementation by
// - Jean-Philippe Goerke (jpgoerke@users.sourceforge.net)
// - Carsten Klein (cklein05@users.sourceforge.net)
//
// Contributors:
// - David Boland (davidboland@vodafone.ie)
//
// Main reference : MSDN Knowledge Base
//
// This file is part of FreeImage 3
//
// COVERED CODE IS PROVIDED UNDER THIS LICENSE ON AN "AS IS" BASIS, WITHOUT WARRANTY
// OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, WITHOUT LIMITATION, WARRANTIES
// THAT THE COVERED CODE IS FREE OF DEFECTS, MERCHANTABLE, FIT FOR A PARTICULAR PURPOSE
// OR NON-INFRINGING. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE COVERED
// CODE IS WITH YOU. SHOULD ANY COVERED CODE PROVE DEFECTIVE IN ANY RESPECT, YOU (NOT
// THE INITIAL DEVELOPER OR ANY OTHER CONTRIBUTOR) ASSUME THE COST OF ANY NECESSARY
// SERVICING, REPAIR OR CORRECTION. THIS DISCLAIMER OF WARRANTY CONSTITUTES AN ESSENTIAL
// PART OF THIS LICENSE. NO USE OF ANY COVERED CODE IS AUTHORIZED HEREUNDER EXCEPT UNDER
// THIS DISCLAIMER.
//
// Use at your own risk!
// ==========================================================

// ==========================================================
// CVS
// $Revision: 1.3 $
// $Date: 2009/02/20 07:41:08 $
// $Id: FIRGB16.cs,v 1.3 2009/02/20 07:41:08 cklein05 Exp $
// ==========================================================

using System;
using System.Drawing;
using System.Runtime.InteropServices;

namespace FreeImageAPI
{
    /// <summary>
    /// The <b>FIRGB16</b> structure describes a color consisting of relative
    /// intensities of red, green, blue and alpha value. Each single color
    /// component consumes 16 bits and so, takes values in the range from 0 to 65535.
    /// </summary>
    /// <remarks>
    /// <para>
    /// The <b>FIRGB16</b> structure provides access to an underlying FreeImage <b>FIRGB16</b>
    /// structure. To determine the red, green or blue component of a color,
    /// use the red, green or blue fields, respectively.
    /// </para>
    /// <para>For easy integration of the underlying structure into the .NET framework,
    /// the <b>FIRGB16</b> structure implements implicit conversion operators to 
    /// convert the represented color to and from the <see cref="System.Drawing.Color"/>
    /// type. This makes the <see cref="System.Drawing.Color"/> type a real replacement
    /// for the <b>FIRGB16</b> structure and my be used in all situations which require
    /// an <b>FIRGB16</b> type.
    /// </para>
    /// <para>
    /// Each color component red, green or blue of <b>FIRGB16</b> is translated into
    /// it's corresponding color component R, G or B of
    /// <see cref="System.Drawing.Color"/> by right shifting 8 bits and shifting left 8 bits for the reverse conversion.
    /// When converting from <see cref="System.Drawing.Color"/> into <b>FIRGB16</b>, the
    /// color's alpha value is ignored and assumed to be 255 when converting from
    /// <b>FIRGB16</b> into <see cref="System.Drawing.Color"/>, creating a fully
    /// opaque color.
    /// </para>
    /// <para>
    /// <b>Conversion from System.Drawing.Color to FIRGB16</b>
    /// </para>
    /// <c>FIRGB16.component = Color.component &lt;&lt; 8</c>
    /// <para>
    /// <b>Conversion from FIRGB16 to System.Drawing.Color</b>
    /// </para>
    /// <c>Color.component = FIRGB16.component &gt;&gt; 8</c>
    /// <para>
    /// The same conversion is also applied when the <see cref="FreeImageAPI.FIRGB16.Color"/>
    /// property or the <see cref="FreeImageAPI.FIRGB16(System.Drawing.Color)"/> constructor
    /// is invoked.
    /// </para>
    /// </remarks>
    /// <example>
    /// The following code example demonstrates the various conversions between the
    /// <b>FIRGB16</b> structure and the <see cref="System.Drawing.Color"/> structure.
    /// <code>
    /// FIRGB16 firgb16;
    /// // Initialize the structure using a native .NET Color structure.
    ///	firgb16 = new FIRGBA16(Color.Indigo);
    /// // Initialize the structure using the implicit operator.
    ///	firgb16 = Color.DarkSeaGreen;
    /// // Convert the FIRGB16 instance into a native .NET Color
    /// // using its implicit operator.
    ///	Color color = firgb16;
    /// // Using the structure's Color property for converting it
    /// // into a native .NET Color.
    ///	Color another = firgb16.Color;
    /// </code>
    /// </example>
    [Serializable, StructLayout(LayoutKind.Sequential)]
    public struct FIRGB16 : IComparable, IComparable<FIRGB16>, IEquatable<FIRGB16>
    {
        /// <summary>
        /// The red color component.
        /// </summary>
        public ushort red;

        /// <summary>
        /// The green color component.
        /// </summary>
        public ushort green;

        /// <summary>
        /// The blue color component.
        /// </summary>
        public ushort blue;

        /// <summary>
        /// Initializes a new instance based on the specified <see cref="System.Drawing.Color"/>.
        /// </summary>
        /// <param name="color"><see cref="System.Drawing.Color"/> to initialize with.</param>
        public FIRGB16(Color color)
        {
            red = (ushort)(color.R << 8);
            green = (ushort)(color.G << 8);
            blue = (ushort)(color.B << 8);
        }

        /// <summary>
        /// Tests whether two specified <see cref="FIRGB16"/> structures are equivalent.
        /// </summary>
        /// <param name="left">The <see cref="FIRGB16"/> that is to the left of the equality operator.</param>
        /// <param name="right">The <see cref="FIRGB16"/> that is to the right of the equality operator.</param>
        /// <returns>
        /// <b>true</b> if the two <see cref="FIRGB16"/> structures are equal; otherwise, <b>false</b>.
        /// </returns>
        public static bool operator ==(FIRGB16 left, FIRGB16 right)
        {
            return
                ((left.blue == right.blue) &&
                (left.green == right.green) &&
                (left.red == right.red));
        }

        /// <summary>
        /// Tests whether two specified <see cref="FIRGB16"/> structures are different.
        /// </summary>
        /// <param name="left">The <see cref="FIRGB16"/> that is to the left of the inequality operator.</param>
        /// <param name="right">The <see cref="FIRGB16"/> that is to the right of the inequality operator.</param>
        /// <returns>
        /// <b>true</b> if the two <see cref="FIRGB16"/> structures are different; otherwise, <b>false</b>.
        /// </returns>
        public static bool operator !=(FIRGB16 left, FIRGB16 right)
        {
            return !(left == right);
        }

        /// <summary>
        /// Converts the value of a <see cref="System.Drawing.Color"/> structure to a <see cref="FIRGB16"/> structure.
        /// </summary>
        /// <param name="value">A <see cref="System.Drawing.Color"/> structure.</param>
        /// <returns>A new instance of <see cref="FIRGB16"/> initialized to <paramref name="value"/>.</returns>
        public static implicit operator FIRGB16(Color value)
        {
            return new FIRGB16(value);
        }

        /// <summary>
        /// Converts the value of a <see cref="FIRGB16"/> structure to a <see cref="System.Drawing.Color"/> structure.
        /// </summary>
        /// <param name="value">A <see cref="FIRGB16"/> structure.</param>
        /// <returns>A new instance of <see cref="System.Drawing.Color"/> initialized to <paramref name="value"/>.</returns>
        public static implicit operator Color(FIRGB16 value)
        {
            return value.Color;
        }

        /// <summary>
        /// Gets or sets the <see cref="System.Drawing.Color"/> of the structure.
        /// </summary>
        public Color Color
        {
            get
            {
                return Color.FromArgb((red >> 8), (green >> 8), (blue >> 8));
            }
            set
            {
                red = (ushort)(value.R << 8);
                green = (ushort)(value.G << 8);
                blue = (ushort)(value.B << 8);
            }
        }

        /// <summary>
        /// Compares this instance with a specified <see cref="Object"/>.
        /// </summary>
        /// <param name="obj">An object to compare with this instance.</param>
        /// <returns>A 32-bit signed integer indicating the lexical relationship between the two comparands.</returns>
        /// <exception cref="ArgumentException"><paramref name="obj"/> is not a <see cref="FIRGB16"/>.</exception>
        public int CompareTo(object obj)
        {
            if (obj == null)
            {
                return 1;
            }
            if (!(obj is FIRGB16))
            {
                throw new ArgumentException("obj");
            }
            return CompareTo((FIRGB16)obj);
        }

        /// <summary>
        /// Compares this instance with a specified <see cref="FIRGB16"/> object.
        /// </summary>
        /// <param name="other">A <see cref="FIRGB16"/> to compare.</param>
        /// <returns>A signed number indicating the relative values of this instance
        /// and <paramref name="other"/>.</returns>
        public int CompareTo(FIRGB16 other)
        {
            return this.Color.ToArgb().CompareTo(other.Color.ToArgb());
        }

        /// <summary>
        /// Tests whether the specified object is a <see cref="FIRGB16"/> structure
        /// and is equivalent to this <see cref="FIRGB16"/> structure.
        /// </summary>
        /// <param name="obj">The object to test.</param>
        /// <returns><b>true</b> if <paramref name="obj"/> is a <see cref="FIRGB16"/> structure
        /// equivalent to this <see cref="FIRGB16"/> structure; otherwise, <b>false</b>.</returns>
        public override bool Equals(object obj)
        {
            return ((obj is FIRGB16) && (this == ((FIRGB16)obj)));
        }

        /// <summary>
        /// Tests whether the specified <see cref="FIRGB16"/> structure is equivalent to this <see cref="FIRGB16"/> structure.
        /// </summary>
        /// <param name="other">A <see cref="FIRGB16"/> structure to compare to this instance.</param>
        /// <returns><b>true</b> if <paramref name="obj"/> is a <see cref="FIRGB16"/> structure
        /// equivalent to this <see cref="FIRGB16"/> structure; otherwise, <b>false</b>.</returns>
        public bool Equals(FIRGB16 other)
        {
            return (this == other);
        }

        /// <summary>
        /// Returns a hash code for this <see cref="FIRGB16"/> structure.
        /// </summary>
        /// <returns>An integer value that specifies the hash code for this <see cref="FIRGB16"/>.</returns>
        public override int GetHashCode()
        {
            return base.GetHashCode();
        }

        /// <summary>
        /// Converts the numeric value of the <see cref="FIRGB16"/> object
        /// to its equivalent string representation.
        /// </summary>
        /// <returns>The string representation of the value of this instance.</returns>
        public override string ToString()
        {
            return FreeImage.ColorToString(Color);
        }
    }
}